In a bidirectional (bi-di) dense wavelength division multiplexing (DWDM) system, two different sets of wavelength channels are used to carry upstream and downstream data traffic in opposite directions in a single fiber. One common example is to use C-band wavelengths for upstream data traffic and L-band wavelengths for downstream data traffic. A second example uses a lower half of C-band (“C−” band) wavelengths for upstream and higher half of C-band (“C+” band) wavelengths for downstream. An edge filter is needed to separate the two sets of wavelengths and a guard-band, for example of approximately 12 nm, is needed to allow the edge filter to separate the two sets of wavelengths. Accordingly, the guard-band takes up a significant portion of the available band and reduces available wavelengths channels in a single fiber.